/* gif.h */

/****************************************************************************\

**  Title:       GIF.H                                                      **
**  Purpose:     GIF Header file                                            **
**  Version:     1.0                                                        **
**  Date:        March 1992                                                 **
**  Author:      James D. Murray, Anaheim, CA, USA                          **
**  C Compilers: Borland C++ v2.0, Microsoft C v6.00a                       **
**                                                                          **
**  This file contains the header structures for the GIF image              **
**  file format.                                                            **
**                                                                          **
**                                                                          **
**  Copyright (C) 1991 by Graphics Software Labs.  All rights reserved.     **
\****************************************************************************/
#ifndef GIF_H
#define GIF_H   1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* #include <curses.h> JSS */

/* #include "datatype.h"        Data type definitions, physically here */
typedef unsigned char BYTE;
typedef signed char   SHORT;
typedef short int     WORD;
typedef int           DWORD;
#undef VOID
#define VOID void

/*
**  The GIF Global Color Table.
**
**  The size of a color table may be any power of two from 2 to 256.
**  We specify the maximum size here for clarity.
*/
typedef struct _GifGlobalColorTable
{
    BYTE    Red;        /* Red Global Color Table Data */
    BYTE    Green;      /* Green Global Color Table Data */
    BYTE    Blue;       /* Blue Global Color Table Data */
} GIFGLOBALCT[256];


/*
**  The GIF Local Color Table.
**
**  The size of a color table may be any power of two from 2 to 256.
**  We specify the maximum size here for clarity.
*/
typedef struct _GifLocalColorTable
{
    BYTE    Red;        /* Red Global Color Table Data */
    BYTE    Green;      /* Green Global Color Table Data */
    BYTE    Blue;       /* Blue Global Color Table Data */
} GIFLOCALCT[256];

                                                               
/*
**  The GIF header format.
**
**  This structure actually contains the header, logical screen
**  descriptor, and the global color table for the GIF image.
*/
typedef struct _GifHeader       /* Offset   Description            */
{
    BYTE        Signature[3];   /*  00h     ID Signature           */
    BYTE        Version[3];     /*  03h     Version Number         */
    WORD        ScreenWidth;    /*  06h     Logical Screen Width   */
    WORD        ScreenHeight;   /*  08h     Logical Screen Height  */ 
    BYTE        PackedField;    /*  0Ah     Color Information      */
    BYTE        ColorIndex;     /*  0Bh     Background Color Index */
    BYTE        AspectRatio;    /*  0Ch     Pixel Aspect Ratio     */
    GIFGLOBALCT GlobalCT;       /*  0Dh     Global Color Table     */
} GIFHEAD;                      


/*
**  The GIF Image Descriptor.
*/
typedef struct _GifImageDescriptor
{
    BYTE        ImageSeparator;     /* Image Descriptor identifier           */
    WORD        ImageLeft;          /* X position of image on the display    */
    WORD        ImageTop;           /* Y position of image on the display    */
    WORD        ImageWidth;         /* Width of the image in pixels          */
    WORD        ImageHeight;        /* Height of the image in pixels         */
    BYTE        PackedField;        /* Image and Color Table Data Information*/
    GIFLOCALCT  LocalCT;            /* Local Color Table                     */
} GIFIMAGEDESC;


/*
**  GIF 89a Graphic Control Extension Block
*/
typedef struct _GifGraphicControlExtension
{
    BYTE    Introducer;         /* Extension Introducer (always 21h)    */
    BYTE    Label;              /* Extension Label (always F9h)         */
    BYTE    BlockSize;          /* Size of Extension Block (always 04h) */
    BYTE    PackedField;        /* Graphic Data Information             */
    WORD    DelayTime;          /* Delay time in hundredths of a second */
    BYTE    ColorIndex;         /* Transparent Color Index              */
    BYTE    Terminator;         /* Block Terminator (always 0)          */
} GIFGRAPHICCONTROL;


/*
**  GIF 89a Plain Text Extension Block
*/
typedef struct _GifPlainTextExtension
{
    BYTE    Introducer;         /* Extension Introducer (always 21h)    */
    BYTE    Label;              /* Extension Label (always 01h)         */
    BYTE    BlockSize;          /* Size of Extension Block (always 0Ch) */
    WORD    TextGridLeft;       /* X position of text grid in pixels    */
    WORD    TextGridTop;        /* Y position of text grid in pixels    */
    WORD    TextGridWidth;      /* Width of the text grid in pixels     */
    WORD    TextGridHeight;     /* Height of the text grid in pixels    */
    BYTE    CellWidth;          /* Width of a grid cell in pixels       */
    BYTE    CellHeight;         /* Height of a grid cell in pixels      */
    BYTE    TextFgColorIndex;   /* Text foreground color index value    */
    BYTE    TextBgColorIndex;   /* Text background color index value    */
    BYTE   *PlainTextData;      /* Plain Text data sub-blocks           */
    BYTE    Terminator;         /* Block Terminator (always 0)          */
} GIFPLAINTEXT;


/*
**  GIF 89a Application Extension Block
*/
typedef struct _GifApplicationExtension
{
    BYTE    Introducer;         /* Extension Introducer (always 21h)    */
    BYTE    Label;              /* Extension Label (always FFh)         */
    BYTE    BlockSize;          /* Size of Extension Block (always 0Bh) */
    BYTE    Identifier[8];      /* Application Identifier               */
    BYTE    AuthentCode[3];     /* Application Authentication Code      */
    BYTE   *ApplicationData;    /* Application data sub-blocks          */
    BYTE    Terminator;         /* Block Terminator (always 0)          */
} GIFAPPLICATION;


/*
**  GIF 89a Comment Extension Block
*/
typedef struct _GifCommentExtension
{
    BYTE    Introducer;         /* Extension Introducer (always 21h)    */
    BYTE    Label;              /* Comment Label (always FEh)           */
    BYTE   *CommentData;        /* Comment data sub-blocks              */
    BYTE    Terminator;         /* Block Terminator (always 0)          */
} GIFCOMMENT;


/*
**  Function Prototypes
*/
/* GIFREAD.C */
int ReadGifHeader(GIFHEAD *GifHead, FILE *FpGif);
int ReadGifImageDesc(GIFIMAGEDESC *GifImageDesc, FILE *FpGif);
int ReadGifGraphicControl(GIFGRAPHICCONTROL *GifGC, FILE *FpGif);
int ReadGifPlainText(GIFPLAINTEXT *GifPlainText, FILE *FpGif);
int ReadGifApplication(GIFAPPLICATION *GifApplication, FILE *FpGif);
int ReadGifComment(GIFCOMMENT *GifComment, FILE *FpGif);
WORD  GetWord(FILE *FpGif); /* little endian */
BYTE  GetByte(FILE *FpGif);
DWORD GetDword(FILE *FpGif);
VOID  GetString(char * str, int len, FILE *FpGif);
VOID  PutWord(WORD x, FILE *FpGif);
VOID  PutByte(BYTE x, FILE *FpGif);
VOID  PutDword(DWORD x, FILE *FpGif);
VOID  PutString(char * str, int len, FILE *FpGif);

#endif  /* GIF_H */